Tape closure assemblies for containers are known which utilize two or three-tape closure systems for a pour hole in the container end. Such systems include the combination of an interior tape covering the pour hole on the inner side of the container end, an exterior tape which covers the pour hole on the exterior surface of the container, and a pull tab extending over a portion of the exterior tape to facilitate grasping the tape and opening the container.
For paper containers or cartons, the method generally used in assembling such a system includes providing a base paper stock which is coated with a polyethylene or similar extruded coating on its outer surface. An aluminum foil is laminated to the back side or inner surface of the paper stock, and a further polyethylene or similar material is extruded over the foil to thereby make the container impermeable to liquid contents. The structure provides the finished web stock for the cartons or containers which is then slit into individual widths and utilized as roll stock material. Such roll stock may be further finished to basic individual sheet stock depending on the next step of the process. Typically, a straw hole or pour hole may be then punched through the entire laminate structure which then must be covered by a closure assembly.
A container constructed in this manner is then ready to enter the first stage of the filling process once a suitable easy opening closure assembly is adhered over the die cut pour hole. A pressure sensitive or heat activated peel open single-faced tape is applied to the top of the carton stock over the die cut pour opening. Since the adhesive on the tape and the edge of the pour hole are exposed to the fill material where the die cut hole is, a second tape must be applied to the underside of the exterior tape to act as a barrier to the contents of the container. A grip tab tape may then be further applied to the exterior tape to provide an area for easy grasping and activation of the pull tab.
The carton stock is then ready to proceed to the actual filling operation to finish the process. Two such systems which have previously been employed are disclosed in U.S. Pat. No. 4,445,620, issued May 1, 1984, to Brochman, et al., and U.S. Pat. No. 4,163,506, issued Aug. 7, 1979, to Patterson. These patents employ the basic two-tape system, and may incorporate a third tape as described above for the pull tab operation. These patents further incorporate additional structure such as a flexible tear template being bonded to the interior and exterior tapes of the closure system, or an alternate means for forming a grip or pull tab and hold-down means therefore.
Such closure systems have more recently been utilized in aseptic container systems wherein the base paper stock, as described above, is used instead of aluminum cans or the like. In aseptic systems, it is important that the closure system does not compromise the integrity of the container contents. For this reason, the second tape or barrier tape as described above has been utilized. In such an aseptic container, it has been found that the edges of the barrier tape or interior tape that are exposed to the fill material may still compromise the integrity of the container. Because of the exposed edges, fill material containing orange or fruite juices, and oils having an acidic base, cannot be used with this system, as the oils will tend to attack the exposed edges and the adhesive thereon to compromise the system. This is true especially when using pressure sensitive type tape systems.
Another problem found with the closure system described is that normally the paper stock is sheet fed in order to apply the interior and exterior tapes of the closure system. By manufacturing the container in this manner, the production is relatively slow and restricts the feed rate of the filling operation.
The two or three-tape closure system also must use additional materials, and includes the additional steps to apply the separate tapes during assembly which increase the cost of such a system. The present invention provides a tape closure system which overcomes the deficiencies of the prior art, and forms an easily opened yet simplified and effective closure system which is particularly advantageous for use in aseptic container systems, but may be used in non-aseptic applications.